Led lighting device

ABSTRACT

A lighting device ( 10 ) is provided which uses multiple LEDs to illuminate a target area. The lighting device includes first and second light emitting diodes ( 24, 26 ) spaced apart from each other. A first convex magnifier lens ( 34 ) is arranged in a light path of the first light emitting diode ( 24 ) for focusing light onto a target area. A second convex magnifier lens ( 36 ) is arranged in a light path of the second light emitting diode ( 26 ) for focusing light onto the same target area. The first and second magnifier lenses ( 34, 36 ) are supported relative to the first and second light emitting diodes ( 24, 26 ) , respectively, by a cover ( 32 ).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/390,245, filed Jun. 20, 2002, the entire disclosure of which ishereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to portable lighting devices(e.g., flashlights) and, more particularly, to a lighting device usingmultiple light emitting diodes (LEDs) as the light source.

Many light illuminating devices, such as flashlights, typically employan incandescent lamp as the light source. Light emitting diodes (LEDs)offer many advantages over conventional incandescent lamps. LEDs aredurable, have a lamp life of about 8,000 hours; and because they operateat low current drains, the useful life of energy storage batteriespowering LEDs is extended. Despite these advantages, there are certainaspects of LEDs which limit their usefulness in certain applications,such as in portable lighting devices. The best standard 5 mm white LEDscurrently available on the market are typically rated at about 3.6volts, 30 milliamps (mA), and produce less than four (4) lumens oflight. In comparison, an incandescent lamp used in conventional lightingdevices with a similar voltage rating will typically produce lightoutput that can range from less than ten (10) lumens to greater thanforty (40) lumens or anywhere in between.

A solution to overcome the limitation of the LED currently beinginvestigated is to use multiple LEDs as the light source in the lightingdevice. Some portable lighting devices currently use up to ten (10), oreven more, LEDs as the light source, which increases the cost of thelighting device. Additionally, the light rays emitted by each LED aredispersed (e.g., forty degrees), and simply using multiple LEDs as thelight source does not cure this problem.

One further approach to the solution is disclosed in U.S. Pat. No.5,174,649 which employs one or more LEDs that illuminate portions of asingle refractive lens element having hyperboloidal surfaces whichtranslate the LEDs emitted rays into substantially parallel beams withinthe single refractive lens element. Another approach employing multipleLEDs in a flashlight is disclosed in U.S. Pat. No. 6,485,160 whichemploys multiple reflector wells, each housing an LED and a lens. Whilesuch approaches provide some directivity and concentration of light raysemitted from multiple LEDs, drawbacks still exist. For example, theformation of a complex refractive lens element and the requirement ofthe multiple reflector wells add to the cost and complexity of thelighting device.

In view of these disadvantages, it would be desirable to have anLED-based lighting system for a portable lighting device, which emittedlight in a directed and concentrated manner.

SUMMARY OF THE INVENTION

In accordance with the teachings of the present invention, a lightingdevice is provided which uses multiple LEDs to illuminate a target area.The lighting device includes a housing and first and second lightemitting diodes located on the housing and spaced from each other. Thelighting device also includes a first magnifier lens arranged in a lightpath of the first light emitting diode for focusing a first light beamonto a target area, and a second magnifier lens arranged in a light pathof the second light emitting diode for focusing a second light beam ontothe target area The lighting device further has a support member forsupporting the first and second magnifier lenses relative to the firstand second light emitting diodes, respectively.

In another aspect of the present invention, the support member is acover extending over the front of the housing, and the cover has anon-reflective inner wall. In a further aspect of the present invention,the lighting device comprises first and second convex magnifier lenses.The axes of the first and second LEDs are parallel to each other, andeach magnifier lens is positioned orthogonal to the axis of the firstand second LEDs, respectively.

The lighting device of this invention takes advantage of the positiveattributes of LEDs, while minimizing costs. The lighting device isdesigned to produce a spotlight beam from each individual LED andmagnifier lens combination which overlaps with the spotlight beamproduced by each adjacent LED and magnifier lens combination. The targetarea is illuminated with a substantially single spotlight beam whichshows excellent symmetry and high, uniform intensity.

These and other features, advantages and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims and appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a headlamp lighting device utilizing themultiple LED lighting system of the present invention;

FIG. 2 is an exploded view of the lighting device of FIG. 1;

FIG. 3 is a cross-sectional view of the front portion of the lightingdevice;

FIG. 4 is a top view layout of the multiple LEDs and magnifier lenses inthe lighting device of the present invention; and

FIG. 5 is a reduced top view layout of the multiple LEDs and magnifierlenses, further illustrating the resultant spotlight beam coverage.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a lighting device 10 is shown employing multiplelight emitting diodes (LEDs) and multiple magnifier lenses according toone embodiment of the present invention. The lighting device 10 is shownas a headlamp flashlight (e.g., spotlight) having an adjustable strap 16adaptive to be worn on the head of a user. While the lighting device 10is shown and described herein as a headlamp flashlight, it should beappreciated that the lighting device 10 may be employed in any of anumber of lighting systems to provide light illumination to a targetarea.

As shown in FIGS. 1-3, the lighting device 10 generally includes a rearhousing 14 connected to an adjustable strap (headband) 16. The rearhousing 14 provides a compartment for housing a plurality of energystorage batteries 52 (e.g., AA-type alkaline batteries) which serve asthe electrical power source. The lighting device 10 further includes afront housing assembly 12 containing the light source and light focusingcomponents of the lighting device 10. The front housing assembly 12 hasa molded housing 18 forming the rear and side walls. Located within thehousing 18 is a printed circuit board 20 having a light control switch22 and other electrical circuitry (not shown) for controllingenergization of the lighting device 10 by controlling the application ofelectrical current from the power source to the light source. Accordingto one embodiment, the control switch 22 is a manually-actuated,three-position switch having a first position in which all the LEDs areturned off, a second position to turn on two LEDs, and a third positionto turn on a third LED.

The lighting device 10 includes, as the light source, a plurality oflight emitting diodes (LEDs) that are shown connected to the printedcircuit board 20 which, in turn, is connected to housing 18. The LEDsinclude a first LED 24 spaced from a second LED 26 for generating firstand second light beams, respectively. Also shown disposed between firstand second LEDs 24 and 26 is a third LED 28 for emitting a third lightbeam. The LEDs 24, 26, and 28 used as the light source in the lightingdevice 10 of the present invention are commercially available from avariety of sources. One example of a commercially available white LED isModel No. NSPW500BS available from Nichia Corporation. It should beappreciated that various kinds of LEDs are readily available fromseveral commercial suppliers. The LEDs 24, 26, and 28 can be of anycolor, depending upon the choice of the users. According to oneembodiment, the first and second LEDs 24 and 26 are white LEDs made byNichia Corporation, and the third LED 28 is a red-colored LED.

The lighting device 10 also includes an inner cover 30 fastened to fronthousing 18 to provide a covering over the printed circuit board 20.Inner cover 30 has openings for allowing the first, second, and thirdLEDs 24-28 to extend therethrough forward of the inner cover 30.Assembled to the front of inner cover 30 is an outer cover and supportmember 32 that covers the front face of cover 30 forward of LEDs 24, 26,and 28. Outer cover and support member 32 supports the first and secondmagnifier lenses 34 and 36 and forms a cover on front housing 18. Theinner wall of outer cover and support member 32 is non-reflective, andthus does not reflect any substantial light rays. The first and secondmagnifier lenses 34 and 36 may be integrally formed within the outercover and support member 32 or may otherwise be attached to outer coverand support member 32. According to one embodiment, the outer cover andsupport member 32 is made of a polymeric material (e.g., plastic) andthe magnifier lenses 34 and 36 are integrally formed within thepolymeric material. In a further embodiment, cover member 32 is made ofa substantially transparent material that allows light rays to passthrough.

The magnifier lenses 34 and 36 are light transparent optics magnifiersthat magnify light transmitted through the lens and direct the magnifiedlight in a light beam. The magnifier lenses 34 and 36 may each beconfigured as a double convex magnifier lens as shown, according to oneembodiment. According to another embodiment, the magnifier lenses 34 and36 may each include a plano convex magnifier lens. The magnifier lenses34 and 36 each have at least one convex surface to provide magnificationto focus the light beam. The magnifier lenses 34 and 36 can be made ofany transparent material, such as glass or polymer (e.g.,polycarbonate). The dimensions of the magnifier lenses 34 and 35 canvary depending upon the spotlight diameter desired by the user. Themagnifier lenses 34 and 36 used in the present invention arecommercially available from a variety of sources and may each include apolycarbonate double convex magnifier lens having Model No. NT32-018,commercially available from Edmund Industrial Optics, having a diameterof nine millimeters (9 mm) and a focal length of nine millimeters (9mm).

Electrical power lines 54 and 56 extend between the printed circuitboard 20 within the front housing 18 and the energy storage batteries 52located in rear housing 14. The electrical power lines 54 and 56 supplyelectrical current (e.g., direct current) from the batteries 52 to theLEDs 24-28 to power the LEDs 24, 26, and 28 which generate thecorresponding light beams. According to one embodiment, the third LED 28may be illuminated separate from LEDs 24 and 26 to provide a light beamof a different color as compared to LEDs 24 and 26. According to oneembodiment, LEDs 24 and 26 provide a white light beam, while LED 28provides a red colored light beam.

Formed at the bottom of front housing assembly 12, along the bottom edgeof support member 32, is a hinge assembly 58 that is connected to therear housing 14. Hinge assembly 58 is rotatable about a horizontal axisto allow the front housing assembly 12 and corresponding LED 24-28 andmagnifier lenses 34 and 36 to rotate relative to the rear housing 14.This enables a user to rotate front housing assembly 12 to adjust theheight positioning of the illuminating light beams.

The lighting systems arrangement of the LEDs 24-28 and magnifier lenses34 and 36 is best illustrated in FIGS. 3 through 5. First and secondLEDs 24 and 26 are arranged relative to magnifier lenses 34 and 36 toproduce first and second light beams 44 and 46, respectively. The firstLED 24 illuminates the first magnifier lens 34 to generate a first lightbeam generally within a defined full angle field of view of about fortydegrees (40°). Substantially all of the light generated by the first LED24 is illuminated onto the first magnifier lens 34 which magnifies andredirects the first light beam in a path shown in FIGS. 4 and 5 bydashed lines 44. The second LED 26 likewise illuminates the secondmagnifier lens 34 to generate a second light beam within a defined fullangle field of view of about forty degrees (40°). The light beamgenerated by the second LED 26 is illuminated onto the second magnifierlens 36 which refocuses and directs the light beam in a second pathshown by dashed lines 46.

Light beams 44 and 46 are shown substantially overlapping andsubstantially cover a common target area 50 to form a single spotlighthaving excellent symmetry and uniform intensity. By employing thearrangement of the first and second LEDs 24 and 26 and magnifier lenses34 and 36, respectively, focused onto a single target area 50, increasedbrightness illumination is achieved in target area 50.

The third LED 28 is shown generating a light beam in a path shown byphantom lines 48 that extends substantially between an opening betweenmagnifier lenses 34 and 36. The light beam 48 generated by LED 28 isemitted within a full angle wide field of view of about forty degrees(40°). Accordingly, a substantial portion of the light beam 48 generatedby a third LED 28 is not directed through a magnifier lens and, hence,is not magnified and focused onto the focal target area 50. Instead, thethird LED 28 illuminates a wider angle of coverage and, thus, operatesmore as a floodlight.

Each of the three LEDs 24-28 includes an electrically powered diodeshown as diodes 24A, 26A, and 28A, respectively. The diodes 24A, 26A,and 28A generate light rays in response to the application of electricalcurrent. Each of the diodes 24A, 26A, and 28A are shown enclosed withina transparent housing 24B, 26B, and 28B, respectively. While lamp-typeLEDs are shown and described herein, it should be appreciated that otherLEDs maybe employed in the lighting device 10.

The first and second LEDs 24 and 26 are spaced apart from each other bydistance D which is measured from the center of the LEDs. In oneembodiment, distance D is about 18.2 mm. The magnifier lenses 34 and 36can be glass (SF5) double convex magnifier lenses which, in oneembodiment, are 9 mm in diameter with a 9 mm effective focal length.Magnifier lens 34 is positioned orthogonal to first LED 24, whilemagnifier lens 36 is positioned orthogonal to second LED 26. The centralfocal axes of first and second LEDs 24 and 26 are parallel to eachother. The surface of the magnifier lenses 34 and 36 can be placed fromthe tip of their respective LEDs at a distance L_(A) and L_(B) to allowfor a back focal length of 7.9 mm, according to one embodiment. This isthe distance L_(A) and L_(B) between the focal point within the firstand second LEDs 24 and 26 and the surface of the corresponding lenses 34and 36, respectively.

The spotlight beam produced from the first LED 24 and magnifier lens 34combination substantially overlaps with the spotlight beam produced fromthe second LED 26 and magnifier 36 combination. The overlap may be lessthan a complete overlap of light beams 44 and 46 due to the offsetarrangement of the perpendicular LED 24 and 26 and magnifier lenses 34and 36 combinations. However, the combination of LEDs 24 and 26 andmagnifier lenses 34 and 36 can result up to a two hundred percent (200%)increase in beam intensity, as compared to a single LED alone.

Accordingly, the lighting device 10 of the present inventionadvantageously produces an enhanced intensity and uniform spot beamfocused onto a target area 50 by employing multiple LEDs at a minimalcost. While light beams 44 and 46 do not completely overlap when offsetmagnifier lenses 34 and 36 are arranged orthogonal to LEDs 24 and 26,the resultant light beams 44 and 46 do substantially overlap in targetarea 50. The overlapping target area 50 could further be refined bytilting magnifier lenses 34 and 36 towards a common target area so as tofocus beams 44 and 46 onto an overlapping target area. However, thetilting of magnifier lenses 34 and 36 may change the shape of theresultant light beams 44 and 46.

The power source used in the light system of the present invention canbe any conventional power source. AC and DC current can be used.Conventional dry cell batteries, for example, zinc/MnO₂, carbon/zinc,nickel metal hydride, or lithium-based electrochemical cells can all beused.

It will be understood by those who practice the invention and thoseskilled in the art, that various modifications and improvements may bemade to the invention without departing from the spirit of the disclosedconcept. The scope of protection afforded is to be determined by theclaims and by the breadth of interpretation allowed by law.

1. A lighting device comprising: a housing; a first light emitting diodelocated on the housing; a second light emitting diode located on thehousing and spaced from the first light emitting diode; a firstmagnifier lens arranged in a light path of the first light emittingdiode for focusing a first light beam onto a target area; a secondmagnifier lens arranged in a light path of the second light emittingdiode for focusing a second light beam onto the target area; and asupport member for supporting the first and second magnifier lensesrelative to the first and second light emitting diodes, respectively. 2.The lighting device as defined in claim 1, wherein the support membercomprises a non-reflective inner wall.
 3. The lighting device as definedin claim 1, wherein the support member comprises a cover of the housing.4. The lighting device as defined in claim 3, wherein the covercomprises a substantially transparent material.
 5. The lighting deviceas defined in claim 1, wherein the first and second magnifier lenseseach comprise a convex magnifier lens.
 6. The lighting device as definedin claim 1, wherein the first and second magnifier lenses each comprisea piano convex magnifier lens.
 7. The lighting device as defined inclaim 1, wherein the first and second magnifier lenses are arrangedsubstantially orthogonal to the light path of the corresponding firstand second light emitting diodes.
 8. The lighting device as defined inclaim 1, wherein the device is employed on a flashlight.
 9. The lightingdevice as defined in claim 1 further comprising a circuit board fixed tothe housing, wherein the first and second light emitting diodes areconnected to the circuit board.
 10. A lighting device comprising: ahousing; a first light emitting diode located on the housing; a secondlight emitting diode located on the housing and spaced from the firstlight emitting diode; a first magnifier lens comprising a convex surfaceand arranged in a light path of the first light emitting diode forfocusing a first light beam onto a target area; a second magnifier lenscomprising a convex surface and arranged in a light path of the secondlight emitting diode for focusing a second light beam onto the targetarea, wherein the second magnifier lens is spaced from the firstmagnifier lens; and a cover disposed over a front of the housing, saidcover supporting the first and second magnifier lenses relative to thefirst and second light emitting diodes, respectively.
 11. The lightingdevice as defined in claim 10, wherein the cover comprises asubstantially transparent material.
 12. The lighting device as definedin claim 10, wherein the cover comprises a non-reflective inner wall.13. The lighting device as defined in claim 10, wherein the first andsecond magnifier lenses each comprise a convex magnifier lens.
 14. Thelighting device as defined in claim 10, wherein the first and secondmagnifier lenses each comprise a plano convex magnifier lens.
 15. Thelighting device as defined in claim 10, wherein the first and secondmagnifier lenses are arranged substantially orthogonal to the light pathof the corresponding first and second light emitting diodes.
 16. Thelighting device as defined in claim 10, wherein the device is employedon a flashlight.